Various embodiments relate to an apparatus for loading a printed circuit board (PCB) and, more particularly, to a PCB loading apparatus which holds and transfers a PCB for measuring a thickness thereof.
To facilitate mass production of electronic devices having PCBs, it is desirable to be able to measure a priori the thicknesses of layers of the PCBs to be incorporated in the devices.
FIG. 1A shows a conventional PCB inspection system for measuring thicknesses of PCB layers a PCB stack P. The conventional PCB inspection system shown in FIG. 1A includes a PCB loading apparatus 100, a control unit 140 for controlling operations of the loading apparatus 100, an image camera 170 for acquiring positions of the PCB layers to be inspected, and an inspection probe 190 for measuring the thicknesses of the PCB layers.
The PCB loading apparatus 100 includes a vacuum chuck 102, which defines vacuum holes 105 in an upper surface thereof, and a PCB holder 110, which is provided on an upper surface of the vacuum chuck 102 and defines fixing holes 115 penetrating therethrough. The vacuum chuck 102 is configured to generate a vacuum suction force. The number of fixing holes 115 penetrating through the PCB holder 110 is the same as the number of vacuum holes 105. The PCB holder 110 is placed on the vacuum chuck 102 so that the fixing holes 115 communicate with respective vacuum holes 105.
FIG. 1B shows the inspection probe 190 and the stack of PCB layers P of FIG. 1A in more detail.
The inspection probe 190 includes a pair of probe tips 192 to be used for measuring the thicknesses of the PCB layers. The PCB stack P includes an inspection area T having pairs of inspection ports T1, T2 and T3, the number of which is the same as the number of the PCB layers. The inspection ports T1, T2 and T3 are provided with corresponding contact points CP1, CP2 and CP3, respectively, to be contacted by the probe tips 192 for measuring the PCB thicknesses. The contact points CP1, CP2 and CP3 are electrically connected to the PCB layers, respectively.
A process for measuring the thicknesses of the PCB layers using the conventional PCB inspection system will now be described with reference to FIGS. 1A and 1B. When the PCB stack P is loaded onto the PCB holder 110, a vacuum suction force generated from the vacuum chuck 102 is applied to the PCB stack P through the vacuum holes 105 and the fixing holes 115 to hold the PCB stack P on the PCB holder 110. After the loading of the PCB stack P has been completed, alignment of the PCB stack P is carried out based on both a position of the vacuum chuck 102 previously stored in the control unit 140 and a position of the PCB stack P with respect to the vacuum chuck 102 measured by the image camera 170. Based on the result of the alignment, the vacuum chuck 102 transfers the PCB stack P to the inspection probe 190. The inspection probe 190 successively brings the pair of probe tips 192 into contact with the contact points CP1, CP2 and CP3 of the inspection ports T1, T2 and T3 of the PCB stack P, thereby measuring the thicknesses of the PCB layers.
However, the conventional PCB inspection system using the PCB loading apparatus 100 has a number of drawbacks. When the PCB stacks P are loaded onto the PCB holder 110, their positions with respect to the vacuum chuck 102 may differ, e.g., depending on the operator who loads the PCB stacks P. Therefore, whenever a PCB stack P is loaded, alignment must be performed, resulting in increased inspection time.
Furthermore, the PCB stack P is held on the PCB holder 110 only by the vacuum suction force of the vacuum chuck 102. Thus, after the vacuum chuck 102 transfers the PCB stack P to the inspection probe 190, its position with respect to the vacuum chuck 102 may change from that used for the alignment. In this case, the probe tips 192 may not exactly come into contact with the contact points CP1, CP2 and CP3 of the inspection ports T1, T2 and T3, thereby compromising the reliability of the inspection process.
Accordingly, there exists a need for an apparatus capable of carrying out a PCB measurement operation in less time with enhanced reliability.